Preliminary study on lost mold casting technology

EPC technology, referred to as “the EPC, also known as gasification casting mold casting, is the traditional wooden other regular shape to switch to plastic foam shape instead of an entity, a firm of modelling, this kind of casting method, after making good blank, don’t remove appearance, but directly poured into good all kinds of metal melting liquid on appearance,After high temperature of metal liquid, under the action of will to that of foam plastics, high temperature heating gasification combustion finally disappear, melts the metal liquid, will replace the original foam plastic shape space position in the sand box, metal solution after cooling, solidified at room temperature, can obtain the required mechanical processing other castings.

1 EPC process flow

The process of EPC is divided into two parts: white area black area.

1.1 Process flow of white area

The white area is the process of making foam models.Foam model production is divided into manual production foaming molding.

1.1.1 Foam forming process

According to the material wall thickness of the casting, choose the foaming bead suitable for it.Then, the original foaming bead is added to the intermittent prefoaming machine for pre-foaming, so that it can reach the required density of the process. After drying in the vulcanization bed of the prefoaming machine, it is sent to the curing chamber for curing.The matured bead is transported to the molding room, the bead is injected into the prefabricated mold on the molding machine. The steam is used to expand melt it to form the casting shape, then the cold water is used for cooling cooling, so that the foamed white mold has the same strength.

1.1.2 Manual molding process

First of all, according to the blank drawing, the prefabricated blank is divided into several modules, then the special tool is used to cut each module on the selected foam board, then according to the blank drawing, each module is glued together with glue glue stick, then the United States paper is used to seal each joint well.

In order to ensure the die.it’s strength, stiffness surface quality, choice of the density of foam board can’t too low, the bubble of the slab good bonding strength between each bead, bead can neither, there is a big gap between at the same time also can’t have too many impurities, in general cases, the die.it need to be made by EPS material, bubble billet surface finish requirement is higher,Die.it mechanical machining methods must be adopted if the future production, the production of die.it surface may produce hair fall off bead produce corrugated concave convex surface the phenomenon such as holes, holes, then in later die.it, must increase the necessary repair, filling process, so as to improve the quality of castings.

The white mold after production is transported to the module room for assembly bonding of the pouring riser.Then the assembled white mold is transported to the paint room for the first dip brush paint.The raw materials for the production of paint will be mixed in the paint mixer according to a certain proportion, the paint density will be tested after the required time is reached. The qualified paint will be put into the paint tank to be used.The soaked brushed white mold will be put on the drying car transported to the yellow mold drying room for drying. The dried yellow mold will be transported to the secondary coating room for secondary dipping brushing, then transported to the yellow mold drying room for drying repair to reach the required coating thickness.The yellow mold after secondary drying will be transported to the molding department of the black area by drying truck for box filling molding.

1.2 Process flow of black area

Put the special interlayer sand box on the vibration working table, put the bottom sand about 100MM thick, spend the shaking table, vibrate the bottom sand, scrape the upper surface.The yellow mould yellow mould model cluster produced in the previous process is placed on the bottom sand of the sand box. After the position is arranged, the sprue sprue nozzle are connected. The sand box is filled with dry sand vibrated in accordance with the specified time of the process.The mouth of the packed box is covered with plastic film, the sprue cup is placed at the sprue, the edge of the box body is pressed with quartz sand.The pipeline under the vacuum system hoses connected to the case, to start the vacuum system vacuum vacuum operation, the time schedule of the technique technological requirements of dry sand tightness after, will have good molten metal casting solution through sprue cup poured onto Huang Mo, waiting for the die.it gasification disappear, high temperature metal liquid instead of die.it position, out of the gate, after pouring.After the casting is completed, the pressure holding cooling is carried out. After the pressure holding, the vacuum butt machine is reset removed. After the pressure holding, it enters the cooling section for cooling.After the casting has condensed, turn over the box remove the casting the loose dry sand.

2. Disappear the advantages of die casting process

Because of the polystyrene foam, the density is very small, so the labor intensity of the workers in the operation process is low.Using lost mold casting technology, compared with the traditional casting method, because of the cancellation of the core production, so can greatly simplify the molding process, casting sand processing process is relatively simple, in the process of processing white mold transportation, it is also easy to achieve mechanization automation of production.Due to the good fluidity of dry sand molding, the sand mixing equipment is exempted, the molding compacting equipment is simplified, so the noise dust can be greatly reduced.The lost mold casting method cancels the core production, the precision of the blank casting is higher.In the process of pouring, the white mold material is decomposed gasified under the action of high temperature. The waste gas such as CO CO2 produced in the production process is a lot, these generated waste gas can be connected to the dust collector for optimal treatment in the vacuum machine in the process of vacuuming.The whole production line is equipped with dust removal system, the air volume regulating valve is added in each equipment room.The dust concentration in the air is obviously lower than the national standard.